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Formaldehyd - szkodliwy czy nie?

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Luminal CCK and its neuronal action on exocrine pancreatic secretion

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Gut regulatory peptides are produced by mucosal endocrine cells and released both into the circulation as well as into the gut lumen. Following stimulation the distribution between the circulation and gut lumen changes in favor of the gut lumen. In the blood plasma, the biological half-life of gut regulatory peptides is counted in single minutes due to high aminopeptidase activity and liver extraction. In the gut lumen, however, regulatory peptides retain their biological activity much longer, especially in newborn and young animals. A series of studies was performed in neonatal calves and pigs to explore the role of luminal cholecystokinin (CCK) on the regulation of exocrine pancreatic secretion. In anaesthetized neonatal calves, CCK was secreted into the duodenal lumen, and electrical vagal stimulation increased CCK release into the duodenal lumen but not into the circulating blood. In conscious calves, luminal CCK-8 stimulated pancreatic protein secretion by a neurohormonal mechanism dependent on a duodenal mucosal CCK1 receptor and vagal nerve activity. Immunocytochemistry pointed to an association of mucosal CCK1 and CCK2 receptors with neuronal components in the small intestine of neonatal calves. Experiments in calves and pigs with CCK-8 infusions into the duodenal branches of the right gastroepiploic artery confirmed the results of luminal CCK-8 and questioned the physiological relevance of a direct mechanism of CCK on the pancreatic acini.
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The activity of the upper gastrointestinal tract is periodic. It concerns the gastrointestinal and gallbladder motility, gastrointestinal blood flow, gastric, intestinal, pancreatic and biliary secretions, rate of nutrient absorption, and many other physiological events. Nowadays, the periodic activity of the gastrointestinal tract is considered as a basic physiological pattern in conscious animals and humans. Unfortunately, there are considerable species- and age-related as well as individual differences, therefore experimental protocols should consider first describing the individual periodic pattern in the examined animals. A lot of confusion may appear with data interpretation if the periodic activity is neglected, in particular when low physiological-like doses of test substances are used. For instance, the effect of CCK or VIP administration on the exocrine pancreas may differ from negligible effect to strong one depending of the phase of pancreatic secretion. The action of secretagogues on the gastrointestinal tract will also be discussed in terms of the ultradian and circadian cycles.
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Ghrelin in the postnatal development of the gastrointestinal tract

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Ghrelin is a 28-amino acid peptide first isolated from rat and human stomachs. Together with the recently discovered 23-amino acid obestatin, it is derived from proghrelin by posttranslational processing. Cells immunoreactive to ghrelin are widely distributed in the gastric mucosa in domestic and laboratory animals and in humans. Ghrelin plays an important role in energy homeostasis, body weight control, and food intake, whereas obestatin seems to induce the opposite effects. Ghrelin and ghrelin receptor expression have been found in developing gastrointestinal foetal and neonatal tissues, and substantial amounts of ghrelin are present in colostrum, thereby suggesting its presumable role in perinatal development. Ghrelin was shown to positively influence weight gain, increase GH, insulin and cortisol secretion. It also stimulates gastrointestinal tissue structure and function development in weaned animals. Surprisingly, responses in suckling neonates were found to be opposite to those in weanlings. Ghrelin retarded gastric, intestinal and pancreatic development and showed a tendency to reduce body weight gain. Recent studies suggest that the biphasic effect of ghrelin in young rats on pancreas and stomach growth seems to be related to age-dependent changes of the release of anabolic IGF-1. In the perinatal period, obestatin is detected in the rat stomach, pancreas and blood plasma. The obestatin concentration in rats is abruptly reduced after birth, contrasting with an increase in the concentration of acylated ghrelin. Further progressive reduction in pancreas obestatin is observed until weaning.
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The gastrointestinal research in domestic animals in Poland is briefly discussed in the section. The history starts over seventy years ago with the creation of the Department of Animal Physiology at the Veterinary Faculty of Warsaw University. Professor B. Gutowski, the first head of the Department, and his pupils established the School of Gastrointestinal Physiology; renowned for the achievements in physiology of digestion, gastrointestinal motility, pancreas and liver functions, and comparative physiology of domestic ruminants and wild animals. After the WWII the gastrointestinal research has also been initiated in the newly established faculties of veterinary and animal science of the agricultural universities in Lublin (motility, composition of pepsinogen, biliary and pancreas secretion, vitamin and microelement absorption), Szczecin (lipid absorption, lymph formation), Wroc³aw (gastrointestinal and gall bladder motility, bile secretion) as well as in the Institute of Animal Physiology and Nutrition of the Polish Academy of Science (digestion and absorption, development of the gastrointestinal tract in neonates). The research activity was focused on solving the problems faced by animal production in Poland, but it also resulted in a considerable number of physiological findings of an international dimension, and initiated new research areas.
The paper presents abiotic resources which are located in a small town in central Poland. They remain unknown to authorities and inhabitants. For the first time they are illustrated in a scientific paper. The objects of local geological heritage point to geodiversity of this district town in the south-western Mazovia. When the geodiversity is interpreted in a simple, an understandable way, it may become attractive for tourists. We show how abiotic resources located within an urban area can be used to support urban geotourism development. The scientific, educational and aesthetic values of these resources may create the town image in accordance with the principles of environmental protection.
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